Filament support



2&36326 Feb, 311, 1936. R. c. SHERMUND FILAMENT SUPPORT Filed May 22, 1935 INVENTOR.

I 1 I I Patented Feb. 11, 1936 UNITED STATES PATENT OFFICE FILAMEN T SUPPORT Application May 22, 1935, Serial No. 22,723

3 Claims.

My invention relates to a filament support for thermionic tubes and more particularly to a filament support adapted to carry current to a plurality of parallel filaments.

Among the objects of my invention are: To provide a two-lead filament support for a plurality of filaments connected in parallel; to provide a two-lead filament support which is adapted to carry a varying number of parallel filaments; and to provide a simple and easily manufactured filament support for energizing parallel filaments.

Other objects of my invention will be apparent or will be specifically pointed out in the description forming a part of this specification, but

I do not limit myself to the embodiment of the invention here described, as various forms may be adopted within the scope of the claims.

The drawing illustrates a longitudinal view, partly in elevation and partly in perspective, of a preferred embodiment of my invention; and the broad aspects thereof may be more readily understood by reference to a detailed description of the embodiment illustrated.

A thermionic tube envelope I, the size and shape of which is not material to the present invention, is provided with a means for sealing relatively heavy leads therethrough, preferably a stem fused in the usual manner in one end of the envelope and carrying cathode leads 4 sealed through the press 5 thereof. I prefer to use two relatively heavy cathode leads and place between them a spring support rod 6 extending axially through the tube.

As I wish to mount a, plurality of filaments energized in parallel on the two leads 4 I prefer to bend the leads in several directions, so that they will cooperate to present in a single plane a number of attachment points for the leg ends of inverted V shaped filaments I. The bights 9 of the filaments are supported by filament springs I0 attached to an upper spring support disc H and extending through apertures in the lower filament spring support disc l2, the discs being spaced to allow room for the springs between them, both being solidly attached to the center spring support 6.

For purposes of illustration I have shown surrounding the filament assembly an anode I4 supported by anode leads I5 sealed through an upper stem I5. I donot, however, wish to be in any way limited to auxiliary structure, as the anode I4 is shown for purposes of illustration only and the tube may be supplied, in addition to an anode, with various other electrodes, such as grids or similar structures which are useful when a pure electron discharge is to be controlled, or where the tube is to be used as a grid-controlled arc rectifier.

The essence of the present invention is embodied in the particular manner by which the cathode leads 4 are bent within the tube to provide attachment points preferably in the same horizontal plane for the leg ends of the filament 1. The cathode leads 4 are brought for a distance inside the tube parallel to the axis as uprights ll-Il. Each of the uprights is then bent to form a horizontal extension I9. These horizontal extensions are preferably parallel and spaced from each other. Each lead is then bent downwardly to form vertical legs 20, and thus the two bent leads form attachment elbows 2|.

The leads are again bent to pass across and below the horizontal extensions l9 and are again maintained parallel and spaced. The ends of the leads are then bent upwardly to terminate in the plane of the elbows 2| at approximately midway of the extensions l9 and spaced therefrom. Terminals 22-22 will form with elbows 2i a rough circle or, more accurately, a hexagon. The leg ends of the filaments are then attached either between a terminus 22 and an elbow 2|, or between elbows 2l-2I, so that each filament will contact first one lead and then the other, thus giving a support for the leg ends of either six V shaped filaments or, with the same structure, by leaving out every other one, three filaments, all operating in parallel. As the filaments operate in parallel all bights 9 are at the same potential and need not be insulated.

Such a structure as has above been described is exceptionally simple and efficient in supplying current to a plurality of filaments. There is good spacing between the leads, and the structure is sumciently open so that welding points may be easily inserted betwen the leads in order to weld the filaments to the elbows or to the termini.

I claim:

1. In combination, a thermionic tube envelope having an inwardly projecting stem, a single pair of current supply leads sealed through said stem, said leads being bent to form a pair of spaced horizontal extensions, and again bent downwardly to form spaced adjacent elbows, and still again bent each lead to pass under the other, and finally rising to terminate in the plane of said extensions, and a plurality of electron emitting filaments bridging said leads and connected thereto in the plane of said extensions.

2. In combination, a thermionic tube envelope having an inwardly projecting steam, at single pair of current supply leads sealed through said stem, said leads being bent to form a pair of spaced horizontal extensions, and again bent downwardly to form spaced adjacent elbows, and still again bent each lead to pass under the other, and finally rising to terminate in the plane of said extensions, and spaced therefrom to form a hexagon with said elbows, and a plurality of filaments connected between adjacent angles of the hexagon thus formed.

3. In combination, a thermionic tube envelope having an inwardly projecting stem, a single pair of current supply leads sealed through said stem, said leads being bent toform a pair of spaced horizontal extensions, and again bent downwardly to form spaced adjacent elbows, and still again bent each lead to pass under the other, and finally rising to terminate in the plane of said extensions, and spaced therefrom to form a hexagon with said elbows, a plurality of filaments connected between adjacent angles of the hexagon thus formed, and means for supporting the center of said filaments to position them to roughly describe a cylindrical surface.

RALPH C. SHERMUND. 

